Search

Context: Although there is evidence that endometriosis results from basal endometrium dislocation, the underlying biology is not fully understood. One protein that plays an important role in regulating epithelial proliferation and differentiation is the 63-kDa membrane protein (p63), which is also a marker of basal and reserve cells in the female genital tract., Objective: To determine whether p63 is expressed differently in peritoneal endometriosis, endometriomas, and adenomyosis, as well as in deep endometriotic nodules of the rectovaginal septum and abdominal wall., Design: This study includes a prospective series of consecutive patients (Canadian Task Force classification II-2) from a tertiary care university hospital. Specimens collected from 83 patients (15 peritoneal endometriosis specimens, 22 endometrioma specimens, 36 adenomyosis specimens, and 10 rectovaginal septum/abdominal wall specimens) were evaluated. Diagnostic and operative laparoscopies or laparotomies were performed, and tissue samples were obtained. Immunohistochemistry was used to evaluate p63 expression., Results: Positivity for p63 was detected in 93.3% of the peritoneal endometriosis specimens, 81.8% of the endometrioma specimens, 36.1% of the adenomyosis specimens, and none of the rectovaginal/abdominal wall endometriosis specimens (P < .001). Distribution of p63 immunostaining in the positive specimens was homogeneous., Conclusions: Endometriotic lesions express p63 differently, and some retain the basal/reserve cell immunophenotype. Nevertheless, it remains unclear whether the lack of p63 expression in some lesions is related to the extent of the disease, to its clinical behavior, or to exacerbation of the accompanying symptoms.

Context: p63 is a recently described p53 homologue. Despite structural homology, they have different activities., Objectives: To obtain new insights into the role of p63 in normal and neoplastic breast tissue and to verify the possible association between p63 and p53 in breast carcinomas., Design: Immunohistochemistry in 85 breast carcinomas using p63, smooth muscle actin (1A4), p53, estrogen receptor, and progesterone receptor. The p63-positive cases were submitted to a double-immunolabeling study using p63 with 1A4, cytokeratin 7, and 34betaE12. Clinical data were retrieved from medical files., Results: p63, like 1A4, stained a single and continuous layer surrounding normal breast ductal and alveolar epithelium. In carcinomas, p53 was expressed in 21.17% of carcinomas, whereas p63 was expressed only in poorly differentiated ductal carcinomas (11.76% of cases). p63-positive cells coexpressed 1A4 and 34betaE12, but not cytokeratin 7. Expression of p63 correlated with pathologic staging, tumor size, histologic grading, nodal metastasis, and estrogen receptor negativity., Conclusions: p63 is a specific myoepithelial cell marker in normal breast tissue and is expressed in a minority of breast carcinomas, being seen only in grade III ductal carcinomas. In ductal carcinomas, malignant p63-positive cells have an immunophenotype similar to that of myoepithelial cells, suggesting that these cells originate from a primary progenitor cell that underwent divergent differentiation to ductal and myoepithelial cells during clonal expansion. Our study argues against a direct role in mammary tumorigenesis. However, p53 is rarely coexpressed with p63, suggesting that p63 could act indirectly as an oncogene by inhibiting p53. This hypothesis could also explain why p63 correlated with several other indicators of poor prognosis.